LaLiga chief Javier Tebas has accused those who want to reignite the Super League of "lying more than (Vladimir) Putin".
The breakaway competition, involving 12 teams, six of whom were from the Premier League, was created and quickly binned last year.
Huge fan backlash saw clubs back out but there are now reports suggesting that Barcelona, Real Madrid and Juventus are hoping to relaunch the idea imminently.
UEFA faced backlash to their reformed Champions League plans but president Aleksander Ceferin has singled out Juventus chief Andrea Agnelli for particular criticism.
The Italian was previously chairman of the ECA (European Club Association), but resigned as he looked to push through the Super League proposal.
Ceferin accused the clubs of using Russia 's invasion on Ukraine as a distraction, whilst Tebas went one step further and claimed those involved lie more than the leader of Russia.
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"He [Agnelli] will have to explain it, if he doesn’t explain it, he will be lying," Tebas said.
"A week ago, I think it was in his house there was a meeting of the three teams.
"Now they are saying they don’t want fixed slots, Real Madrid are saying they don’t want the first slot. It is false.
"It is very difficult for the English teams to form part of this competition so they are creating a European league with two categories and the national leagues are the second categories.
"There will be two or three people relegated but there will always be the typical teams - Juventus, Barcelona, Real Madrid. It will be difficult for them to go down.
"They have made enemies of UEFA and the Premier League, whose growth goes against their model.
"We know this, we have got this information. They can say what they want but this is what they are working on.
"Every time I read about it, I get cross, I think they lie more than Putin to be honest.
"They are insisting that introducing this will not affect national leagues. We must be idiots, we must be dumb. But we all say it hurts the national leagues.
"For me it is an insult, I feel humiliated. They will do huge harm."
Agnelli is expected to explain a second version of the Super League sooner rather than later whilst a legal case is also being pursued against UEFA.
Ceferin has said: "They can play their own competition, nobody forbids them. But if they play their own competition, they can’t play in our competition."
He then added: "First, they launched their nonsense of the idea in the middle of a pandemic. Now, we read articles that they are planning to launch another idea now in the middle of a war.
"We are helping in a terrible situation, they are working on a project like that."
